It's that time of the year again when some of the world's most powerful people lock themselves behind closed doors for three days of high-profile discussions.

Known as the world's most secretive meeting, the Bilderberg Meetings, held annually since 1954, will take place from June 9 - 12 in Dresden, Germany.

It has always attracted curiosity, as no one knows quite what is discussed – although topics released ahead of this year's meeting include the vague "Current events" (Brexit, Trump, migrants?). Other topics of discussion include Europe, Russia, cyber-security, geo-politics of energy and commodity prices (Saudi Arabia?) and 'Precariat and the middle class.'

Discussions are held under the strict Chatham House Rule – meaning that participants are free to use the information received, but neither the identity nor the affiliation of the speaker(s), nor that of any other participant, may be revealed.

According to the Bilderberg Meetings website, "participants are not bound by the conventions of their office or by pre-agreed positions. As such, they can take time to listen, reflect and gather insights. There is no desired outcome, no minutes are taken and no report is written. Furthermore, no resolutions are proposed, no votes are taken, and no policy statements are issued."

Over the years, there have been rumors of career launches and future presidents decided at Bilderberg. "Bill Clinton was a conference attendee in 1991, as a mere governor of Arkansas, a year before he was elected U.S. President. Tony Blair was only a shadow minister when he got his invitation … in 1993," said U.K. newspaper The Independent.

Chaired by the head of French insurance giant AXA Group, Henri de Castries, who also happens to be a count, this year's attendees include CEOs of multinationals including Shell, Deutsche Bank, Airbus, and Siemens; politicians such as former U.S. Secretary of State Henry Kissinger, German finance minister Wolfgang Schaeuble, and former head of the European Commission Jose Manuel Barroso. It also includes economists such as the International Monetary Fund's Christine Lagarde and World Economic Forum Chairman Klaus Schwab and lastly, royalty such as the King of the Netherlands.

"With so many politicians present, including three members of the German cabinet, the German military has been drafted in to oversee security," reported the Guardian newspaper.

And if you're wondering how to attend next year's meeting – unfortunately, one can only wait to be invited as there is no application. "Participants are invited because they can offer a different point of view," according to the Bilderberg Meetings website.